Piston ring



July 19, 1955 HSlA-Sl PIEN 2,713,527

PISTON RING Filed Nov. 1, 1951 4 Sheets-Sheet 1 HSlA-Sl PIEN July 19,1955 PISTON RING 4 Sheets-Sheet 2 Filed Nov. 1, 1951 I N V EN TOR. Hs/n-5/ P/EN BY Hrromvsx July 19, 1955 HSlA-Sl PlEN 2,713,527

PISTON RING Filed Nov. 1, 1951 4 Sheets-Sheet 3 T I F as W 22 INVEN TOR.

HS/H-S/ P/E/v flrroeNEY HSlA-Sl PIEN July 19, 1955 PISTON RING 4Sheets-Sheet 4 Filed Nov. 1, 1951 I n'' INVENTOR. 3/4 -5/ p/EN BY (5% WPISTON RING lisia-Si Pien, Drexel Hill, Pa, assignor to WilkeuingManufacturing Company, Philadelphia, Pa., a corporation of DelawareApplication November 1, 1951, Serial No. 254,344

3 Claims. (Cl. 369-45) will conform to the cylinder-wall notwithstandingany ,I

slight out-of-roundness or out-of-cylindrical shape of the cylinder-walldue either to distortion of the cylinder-wall or due to wear, and onewhich will break in readily.

Another object of the present invention is a pistonring which will bearagainst the cylinder-wall with uniform or equalized outward radialpressure and which will eifectviely seal against the cylinder-wall andwhich may have a relatively high unit of contact-pressure per unit ofcontact-area with cylinder-wall, and which will provide adequatelubrication and will not score or scuff the cylinder-wall.

With the above and other objects in view, the present inventioncontemplates a 3-piece or multi-piece composite piston-ring includingtwo (or more) thin flat annulus-shaped cylinder-contacting sealingelements or rails of generally uniform cross-section having a smallaxial dimension so as to present narrow cylinder-contacting surfaces andhaving an axial width substantially less than the depth of thering-receiving groove and being sufiiciently small in radial dimensionand in cross-sectional area as to conform to the cylinder-wall whenpressed thereagainst with uniformly distributed outward radial pressure,and an intervening circumferentially compressible non-bottomingseal-spacing resilient expander having seal-supporting side-lands andoppositely extending seal-engaging projections extending axiallytherefrom at the inner periphery thereof beyond the planes of saidseal-lands and adapted to engage the inner peripheries of said sealingelements resiliently to urge them outwardly with uniformly distributedoutward radial pressure when the ends of the seal-spacing expander abuteach other and when said expander is circumferentially compressed by thesealing elements when the composite piston-ring is mounted in thering-receiving groove of the piston within the cylinder.

The present invention further contemplates 3-piece oilcontrol ringscomprising a pair of thin and generally flat cylinder-contactingoil-scraper sealing rings (or what, for brevity, may also be calledseals) and an intervening spacer and expander; the pair of seals havinggenerally continuous inner and outer peripheries and each having but asingle gap in the circularity thereof to permit it to be spread opensufficiently so that it can be mounted in the ring-receiving groove ofthe piston (and so as to permit the sealing members to be expandedagainst the cylinder-wall by the expander), while the spacer andexpander, which is preferably set slightly inwardly from thecylinder-diameter, is segmented or slotted and given outward resilientpressure, so as to cause it to support the pair of oil-scrapers (orseals) in an outward pressed condition against the cylinder Wall.

nited States Patent 2,713,527 Patented July 1.9, 1955 The piston-ring ofthe present invention may include still other features or combinationsof elements and may be embodied in still other forms, all as will appearmore fully from the following description and accompanying drawings.

For the purpose of illustrating the invention, there are shown in theaccompanying drawings forms thereof which are at present preferred,although it is to be understood that the various instrumentalities ofwhich the invention consists can be variously arranged and organized andthat the invention is not limited to the precise arrangements andorganizations of the instrumentalities as herein shown and described.

In the accompanying drawings in which like reference characters indicatelike parts:

Figure 1 represents a side-elevational view, partly in section, of a3-piece oil-control ring representing one embodiment of the presentinvention, shown mounted in one of the ring-receiving grooves of apiston.

Figure 2 represents an exploded perspective view of the 3-pieceoil-control ring of the present invention.

Figure 3 represents a plan view of a fragmentary portion of the punchedor cut strip of band or ribbon of flat spring-metal, as, for instance,spring-steel, of which the spacer and expander is formed, showing thefirst stage in the formation of said spacer and expander member.

Figure 4 represents a section on line 44 of Figure 3.

Figure 5 represents a View, similar to that shown in Figure 3, of afragmentary portion of the spacer and expander element, shown in itssecond or later stage of development or manufacture, namely, the stagein which the radially-acting seal-engaging lugs or ears have been bentgenerally at right angle to the main body of the spring-strip.

Figure 6 represents a section on line 66 of Figure 5.

Figure 7 represents a view similar to that shown in Figures 3 and 5, ofthe next or a later development stage of the spacer and expander, butprior to its being coiled into a generally circular shape, namely,wherein the entire spring-strip is bent longitudinally along twogenerally parallel lines, to form the generally U-shaped cross-section,with the seal-engaging ears projecting outwardly from the free ends ofthe U-shape.

Figure 8 represents a section on lines 8-8 of Figure 7.

Figure 9 represents a fragmentary portion of the completed spacer andexpander element shown in Figures 7 and 8, but curved into a generallycircular shape.

Figure 10 represents a cross-section of the completed piston-ring, showndisposed in the ring-receiving groove, but on a somewhat larger scale,better to show the details thereof.

Figure 11 represents a modified form of the construction shown inFigures 1 and 10.

Figure 12 represents an elevational View of a piston-ring representinganother embodiment of the present invention, partly in section, showndisposed in the ring-receiving groove of a piston.

Figure 13 represents an exploded perspective view of the piston-ringshown in Figure 12.

Figure 14 represents a perspective view of a strip of flanged drawnmetal of which the spacer and expander of Figures 12 and 13 is formed.

Figure 15 represents a smaller fragmentary perspective view of the samestrip of metal (of Figure 14) with slots punched or cut thereinto,alternately from opposite edges.

Figure 16 represents a fragmentary perspective view of the spacer andexpander (of Figures 12 to 15) after it has been bent into a U shape incross-section and curved into a generally circular formation.

Figure 17 represents a cross-sectional view of the oilcontrol ring ofthe embodiment shown in Figures 12 and 3 13, on a somewhat larger scale,and showing another embodiment.

Figure 18 represents a fragmentary perspective view of the metal stripof which the cylinder-contacting elements, seals or rails of thepiston-ring of the present invention are formed.

Figure 19 represents a fragmentary perspective view of a coil formed ofthe strip of Figure 18, with the outer cylinder-contacting surfaceschromium plated.

The 3-piece oil-control ring of the present invention is formed of anupper thin iiat oil-scraper or oil-control ringelement 21 and a similarlower oil-scraper or oil-control ring-element 22, and an interveningspacer and expander 23 of generally U-shaped cross-section, includingthe base portion 24 and the sides or legs 25 and 26 of the U, and thelaterally projecting ears 27 and 28.

Each oil-scraper 21 and 22, or what for brevity may be called each sealor rail, is preferably made of a fiat band of steel although it may beformed of suitably hard drawn-metal band. The seals 21 and 22 are madeby coiling the band into a coil of suitable diameter (Figure 19) andthen cutting the individual convolutions to form the oil-scrapers orseals from such coil or by coiling such band and cutting ofi eachconvolution as it is formed (one at a time).

The outer cylinder-contacting edges or faces 29 of the seals 21 and 22 Imay plate with chromium, as indicated by the contrasting shading of themarginal Zone 30 in Figures 1, l and 11. The seals or rails 21 and 22are each split" or provided with a gap at one point, as at 31, but areof such diameter that when the gap 31 is approximately closed, theoil-scraper (21 and 22) will be at the diameter of the cylinderindicated by the line 32. This gap 31 is formed when the oil-scraper iscut from the coil, as indicated above.

The spacer and expander 23 is slitted or slotted by means of thealternating slits or slots 33 and 34; the slots 33 intersecting andextending through the entire U-crosssection of the spacer and expanderexcepting only the extreme inner end of the lower leg 26 of the U andthe lower car 28, while the slots 34 intersect and extend through theentire U-cross-section of the spacer and expander excepting only theinner end of the upper leg 25 of the U and the upper ear 27, asindicated particularly in Figures 2 and 9 (and Figures and 16). Thespacer and expander is also provided with a complete gap or break at onepoint in its circumference, as at 35, so that it too may be spread opento permit it to be mounted within the ring-receiving groove 36. The freeends 37 and 38 of the spacer and expander 23 abut each other thenoperatively installed within the ring-receiving groove. The uncompressedspacer and expander 23 is made suitably oversize in circumference, sothat when the seals or rails 21 and 22 are mounted thereon in the mannerindicated in Figures 1, 10, ll, 12 and 17, and the seals or rails 21 and22 are collapsed to their gap-closing or cylinder-diameter, the spacerand expander 23 will be compressed suitably (with the ends 37 and 38thereof abutting); this compression taking place through the slightresilient deformation of the successive base and leg portions 24, 25 and26 of the U-cross-sectioned spacer and expander 23 (Figures 9 and 10).

The spacer and expander 23 is preferably made of suitably temperedspring-steel or other suitable springmetal. A fiat strip, band or ribbonof annealed spring steel of the width 39 is alternately slotted inwardlyfrom its opposite edges, by means of the slots 33 and 34, respectively,as shown in Figures 2, 3 and 9. This may be done on a punch-press bysuitable dies. This leaves behind the intervening narrow portions whichlater form the base portions 24 and leg portions 25 and 26 and the earportions 27 and 28 0f the generally U-cross-sectioned spacer andexpander. Thereafter, the extreme marginal zones of the strip are bent,as indicated in Figures 5 and 6, at generally right angles, to form theear portions 27 and 28. Thereafter, the strip is further bent alongparallel lines 41 and 42, with a slight curvature or fillet at thebends, to form the generally U-shaped crosssection as indicated inFigures 7 and 8. The bends along lines 41 and 42 may be made first andthe terminal ear portions 27 and 28 bent thereafter, or both sets ofbends may be formed simultaneously. These bends may be formed by passingthe slotted strip through suitable forming rolls. The so-formed U-shapedstrip may then be coiled to suitable diameter, and successive turns orconvolutions of the coils then cut off to form individual spacer andexpander members, of one complete circle, as indicated in Figures 2 and9, with the gap 35 therein at the point of the severing cut. The formedspacer and expander 23 is hardened and drawn or tempered to a suitablespring temper or spring hardness.

The outer side-surfaces of the legs 25 and 26 of the spacer and expander23 form side-supporting surfaces or lands for axially supporting theoil-scrapers, seals" or rails 21 and 22. The cars or lugs 27 and 28 abutand bear against the inner peripheries 43 and 44, respectively, of theseals 21 and 22, and exert an outward radial force thereagainst, therebyto expand the seals 21 and 22, with a uniformly distributed outwardradial pressure, against the cylinder-wall 32, as indicated in Figures1, l0 and 11; Without the expander 23 contacting or bottoming againstthe inner wall of the ring-receiving groove 36.

The distance between the two outer seal-supporting side-surfaces orlands of the legs 25 and 26 of the spacer and expander 23 may be justequal to or very slightly less than the diiference between the width ofthe ringreceiving groove 36 and the combined axial widths of the twoseals or rails 21 and 22, so that the legs 25 and 26 will either spacethe seals or rails snugly or loosely between the side-Walls of thering-receiving groove 36. As the U may also be slightly resilient in anaxial direction, slight resilient axially-outward force may be exertedupon the seals 21 and 22, if desired.

By varying the circumferential length and/ or the thickness of the baseportion 24 and legs 25 and 26 of the U, the amount of outward radialpressure exerted upon the seals 21 and 22 may also be varied and set tothe amount most effective for the desired oil-control.

The cross-section of the rails 21 and 22 is preferably symmetrical abouteach of two right-angular axes, as indicated in Figures 1, l0, 12, 18and 19, with the corners slightly rounded or the cross-section may be asshown in Figures 11 and 17.

In the modified embodiment of the present invention shown in Figures 12to 17, inclusive, the spacer and expander 53 is formed of a strip orband of spring metal such as spring-steel, a fragmentary portion ofwhich is shown in Figure 14, which is formed by rolling or drawing, withthe thickened marginal or flange portions 47 and 48. The inner edges ofthe thickened marginal portions 47 and 48 may be more or less at a rightangle to the plane of the strip as indicated in Figure 12 or they may beslightly undercut as indicated in Figure 17. The strip or band isslotted by punching or milling or otherwise cutting the slots 33 and 34,alternately intersecting opposite edges of the strip and being short ofthe opposite flanged portion as indicated in Figures 15 and 16. Theso-slotted band is then bent along two lines designated generally by thenumerals 41 and 42, to form the generally U-cross-sectioned bandalternately slotted through opposite sides, which is then curved into acircular formation indicated in Figures 13 and 16, as indicated above,by coiling the slotted U-cross-sectioned band into a coil of suitablediameter; from which the individual convolutions of the coil are thencut to form the individual expanders 53 shown in Figure 13.

The inner peripheries 43 and 44 of the scraper-rings or seals 51 and 52may, as indicated in Figures 1, 10, ll, l2, l8 and 19, be also slightlybeveled to match the undercut contact-faces of the seal-engaging lugs 47and 48 (Figure 17) so that the outward radial force exerted by theexpander 53 against the inner peripheries of the seals 51 and 52 willalso tend to draw the rings 51 and 52 closely against the outer sides ofthe legs and 26 of the U-cross-sectioned expander 53.

A similar gap is provided in the general circularity of the expander 53,with the free ends 37 and 38 thereof abutting each other when mountedand operatively compressed within the ring-receiving groove 36 of thepiston.

The expander 53 is likewise preferably made of springsteel tempered tosuitable spring temper, but other resilient spring metal may be used.

The sealing rings 51 and 52 are likewise preferably made of steel ofsuitable hardness or other suitable metal, namely, a hardness which willnot score the cylinder wall.

A slight bevel 59 may be provided along the outer periphery of thesealing and oil-control elements 21, 22, 51 and 52, as indicated inFigure 17. These bevels may both face outwardly as indicated in Figure17 or they may both face upwardly, i. e. in the direction of the closedend of the piston as indicated in Figure 11. The amount of beveling maybe increased so as to reduce the width of the cylinder-contactingcylindrical surface and thereby increase the contact pressure per unitof area.

The present invention may be embodied in other specific forms withoutdeparting from the spirit or essential attributes thereof, and it istherefore desired that the present embodiments be considered in allrespects as illustrative and not restrictive, reference being had to theappended claims rather than to the foregoing description to indicate thescope of the invention.

Having thus described my invention, the following is hereby claimed:

1. A 3-piece oil-control piston ring comprising a resilient andcircumferentially compressible seal supporter and expander of generallyU-shaped cross-section with the base of the U spaced inwardly slightlyfrom the cylinder diameter and with the legs of the U extending inwardlyfrom the base of the U and having the innermost ends thereofsubstantially thicker than the main portion of the legs of the U, saidthickened legterminals of the U forming seal-engaging shouldersextending axially outwardly from the legs of the U and having anundercut radially-outward seal-engaging face, said supporter andexpander being slotted through the base and sides of the U, at frequentintervals, with alternate slots extending through opposed thickenedterminal leg portions of the U, the outer sides of the legs of the Uforming seal-supporting lands, and a pair of flat and generallycontinuous seals, each seal having a beveled inner periphery adapted tobe received in said undercut seal-engaging face of its seal-supportingland, said seals being disposed on opposite sides of said supporter andexpander along said seal-lands thereof, with the undercut seal-engagingshoulders of said thickened terminal leg portions being in operativejuxtaposition to and in contact with the inner beveled peripheries ofsaid seals,

thereby to exert an outward radial force upon said seals and to drawsaid seals against the outer surface of the legs of the U When theoil-control ring is compressed to cylinder diameter with the ends ofsaid supporter expander in abutting relation to each other.

2. A spacer and expander for multi-seal piston-rings comprising agenerally circular U-cross-sectioned resilient spring metal band withthe base of the U outermost and with the legs of the U extendinginwardly therefrom, the inner ends of the legs of the U beingsubstantially thicker than the rest of the leg portions, with thethickened terminal portions extending radially outwardly in oppositedirections and forming seal-engaging shoulders extending outwardly fromthe sides of the legs of the U and having an undercut radially-outwardseal-engaging face, said U-cross sectioned spacer and expander havingspaced slots therethrough at frequent intervals, each slot extendingthrough one of the thickened end zones while leaving the oppositethickened end zone intact, and alternate slots extending throughopposite thickened end zones, thereby to form a circumferentiallycompressible spacer and expander.

3. A 3-piece oil-control piston-ring comprising a resilient andcircumferentially compressible seal supporter and expander of generallyU'shaped cross-section with the base of the U spaced inwardly slightlyfrom the cylinder diameter and with the legs of the U extending inwardlyfrom the base of the U and having the innermost ends thereofsubstantially thicker than the main portion of the legs of the U, saidthickened leg-terminals of the U forming seal-engaging shouldersextending axially outwardly from the legs of the U and having anundercut radially-outward seal-engaging face, said supporter andexpander being slotted through the base and sides of the U, at frequentintervals, with alternate slots extending through opposed thickenedterminal leg portions of the U, the outer sides of the legs of the Uforrning seal-supporting lands, and a pair of flat and generallycontinuous seals having chromium-plated outer peripheral edges, eachseal having a beveled inner periphery adapted to be received on saidundercut seal-engaging face of its seal-supporting land, said sealsbeing disposed on opposite sides of said supporter and expander alongsaid seal-lands thereof, with the undercut sealengaging shoulders ofsaid thickened terminal leg portions being in operative juxtaposition toand in contact with the inner beveled peripheries of said seals and todraw said seals against the outer surface of the legs of the U, therebyto exert an outward radial force upon said seals when the oil-controlring is compressed to cylinder diameter with the ends of said supporterexpander in abutting relation to each other.

References Cited in the file of this patent UNITED STATES PATENTS2,220,947 Paton Nov. 12, 1940 2,390,044 Bowers Dec. 4, 1945 2,565,042Phillips Aug. 21, ll 2,635,022 Shirk Apr. 14, 1953

